Grinding disk or bur.



M. R. MARTIN, GBINDINGDISK 0R BUR.

APPLICATION FILED MAY 18, I916.

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ran R. Mari Jmwwwm/L Vfl MYRGN R. MARTIN, OF ST. LOUIS PARK, MINNESOTA.

GRINDING DISK 0R BUR.

Specification of Letters Patent.

Patented Jan. 1, 1918.

Application filed May 1s, 1916. Serial no. 98,374.

To all whom it may concern:

Be it known that I, MYRoN R. MARTIN, a citizen of the United States, and resident of St. Louis Park, Hennepin county, Minnesota, have invented certain new and useful Improvements in Grinding Disks or Burs, of which the following is a specification.

The invention consists in the features hereinafter described and particularly pointed out in the claims.

In the accompanying drawings Figure 1 is a face view of the grinding disk or bur, only a portion of the ribs or grinding surface being shown. I

Fig. 2 is a sectional view on the line 22 of Fig. 1.

Fig. 3 is an edge view showing, however, only a portion of the disk.

Fig. 4c is a view of the inner edge of the disk.

Fig. 5 is a sectional view on line 55 of Fig. 1.

The grinding face of the disk is made up of a series of ribs extending at an inclination to the radii of the disk and with their inner ends in the direction of movement, or in the direction of the grinding action, located in advance of the outer ends of the ribs. The ribs are indicated generally by the characters a, b, 0', etc., and it will be noted that the ribs diverge in respect to their general direction from their inner toward their outer ends. Each rib is serrated, as at 1, on its front edge and it is grooved in rear of this serrated front edge, these grooves being indicated at 2 and extending in the same general direction that the ribs themselves extend, that is at an inclination to the radii of the disk. The grooves are open at their outer ends and they are slightly divergent in respect to each other and they leave supplemental ribbed portions or sections at 3. The grooves and supplemental ribs of each main rib are in stepped relation to each other, the first groove starting at a point nearer to the center of the disk than the next groove and the third groove starting at a point farther out on the disk than the second groove and so on. The grooves open into the spacesbetween the main ribs, and in the particular construction shown each groove starts at a point adjacent to or in rear of one of the teeth or shoulders of the serrated, edge of the main rib. The inner portions of the main ribs from the point 00 to the inner edge of the disk is continuous and substantially plain, that is to say it has no grooved formation nor does it have a serrated formation. In action the front serrated edges of the main ribs will perform the coarse or rough or first grinding action and the supplemental ribs, in rear of this serrated front edge, will perform the finer. grinding actions and the material from these ribs will be discharged into the outwardly flaring spaces y between the main ribs. The'ribs are arranged in groups, such for instance as A, B, and between these groups of ribs the disk is provided with spaces 0, the bottoms of which incline inwardly and downwardly and also circumferentially to the points'D, so that the material to be ground is received in these spaces and passes thence outwardly between the ribs. Furthermore, the inner ends of the ribs progressively incline down- I wardly and inwardly from the upper surface of the disk, it being noticed, for instance, from Fig. 4 that the inner end of the rib at the left of the group is lower than the inner end of the rib at the right of the group. This latter rib is located through.- out substantially in the same plane with the grinding portion or grooved portion of the rib and each rib in advance progressively has its inner end in a lower plane.

WVhere in the appended claims I refer to main ribs 1 refer to the ribslwhich extend from the center opening to the point x and from this pointto the outer edge which latter portion is of zig zag form providing the shoulders or serrations at 1 and the branch ribs are shown at 3.

What I claim is 1. A grinding disk having main ribs inclined from their inner ends backwardly in relation to the direction of rotation and serrated on their front edges, said ribs having branches in rear of the serrated main portion, which branches extend from the points where the serrations occur and lie substantially parallel with the main part of the rib, thereby forming grooves, said grooves being opened at their outer ends which are directed backwardly in relation to the direction of rotation, substantially as described.

2A grinding disk having main ribs inclining backwardly in relation to the direction of rotation and provided with a stepped formation forming serrations or shoulders on their front edges with branches in rear of the main portions extending from the oints where the ste 3s be 'in said branches being coincident with parts of the main rib and parallel with adjacent parts of the main rib and also parallel with adjacent branches, said inain ribs and branches forming grooves with their open ends directed backwardly in relation to the rotative movement of the disk, substantially as described.

3. A grinding disk having main ribs inclining backwardly in relation to the directicn oi? rotation and provided with a stepped iorn'iation forming serrations or shoulders on their front edges with branches in rear of the main portions extending from the points where the steps begin, said branches being coincident with parts of the main rib and parallel with adjacent parts of the main rib and also parallel with adjacent branches, said main ribs and branches forming grooves with their open ends directed backwardly in relation to the rotative movement of the disk, said branches terminating at different distances from the center of the disk, substantially as described.

In testimony whereof, I affix my signature.

MYRON R. MARTIN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, 1). c. 

